On Mon, Oct 11, 2021 at 10:35:37AM -0700, Luis Chamberlain wrote:

On Tue, Oct 05, 2021 at 04:30:06PM +0200, Greg KH wrote:

quoted

On Fri, Sep 17, 2021 at 11:22:16AM -0700, Luis R. Rodriguez wrote:

quoted

From: Luis Chamberlain <mcgrof@kernel.org>

The built-in firmware is always supported when a user enables
FW_LOADER=y today, that is, it is built-in to the kernel. When the
firmware loader is built as a module, support for built-in firmware
is skipped. This requirement is not really clear to users or even
developers.

Also, by default the EXTRA_FIRMWARE is always set to an empty string
and so by default we really have nothing built-in to that kernel's
sections for built-in firmware, so today a all FW_LOADER=y kernels
spins their wheels on an empty set of built-in firmware for each
firmware request with no true need for it.

Add a new kconfig entry to represent built-in firmware support more
clearly. This let's knock 3 birds with one stone:

 o Clarifies that support for built-in firmware requires the
   firmware loader to be built-in to the kernel

 o By default we now always skip built-in firmware even if a FW_LOADER=y

 o This also lets us make it clear that the EXTRA_FIRMWARE_DIR
   kconfig entry is only used for built-in firmware

Reviewed-by: Borislav Petkov <redacted>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 .../driver-api/firmware/built-in-fw.rst       |  2 ++
 Documentation/x86/microcode.rst               |  5 ++--
 drivers/base/firmware_loader/Kconfig          | 25 +++++++++++++------
 drivers/base/firmware_loader/Makefile         |  3 +--
 drivers/base/firmware_loader/main.c           |  4 +--
 5 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/Documentation/driver-api/firmware/built-in-fw.rst b/Documentation/driver-api/firmware/built-in-fw.rst
index bc1c961bace1..9dd2b1df44f0 100644
--- a/Documentation/driver-api/firmware/built-in-fw.rst
+++ b/Documentation/driver-api/firmware/built-in-fw.rst

@@ -8,6 +8,7 @@ the filesystem. Instead, firmware can be looked for inside the kernel
 directly. You can enable built-in firmware using the kernel configuration
 options:
 
+  * CONFIG_FW_LOADER_BUILTIN
   * CONFIG_EXTRA_FIRMWARE
   * CONFIG_EXTRA_FIRMWARE_DIR
 

@@ -17,6 +18,7 @@ into the kernel with CONFIG_EXTRA_FIRMWARE:
 * Speed
 * Firmware is needed for accessing the boot device, and the user doesn't
   want to stuff the firmware into the boot initramfs.
+* Testing built-in firmware
 
 Even if you have these needs there are a few reasons why you may not be
 able to make use of built-in firmware:

diff --git a/Documentation/x86/microcode.rst b/Documentation/x86/microcode.rst
index a320d37982ed..d199f0b98869 100644
--- a/Documentation/x86/microcode.rst
+++ b/Documentation/x86/microcode.rst

@@ -114,11 +114,12 @@ Builtin microcode
 =================
 
 The loader supports also loading of a builtin microcode supplied through
-the regular builtin firmware method CONFIG_EXTRA_FIRMWARE. Only 64-bit is
-currently supported.
+the regular builtin firmware method using CONFIG_FW_LOADER_BUILTIN and
+CONFIG_EXTRA_FIRMWARE. Only 64-bit is currently supported.
 
 Here's an example::
 
+  CONFIG_FW_LOADER_BUILTIN=y
   CONFIG_EXTRA_FIRMWARE="intel-ucode/06-3a-09 amd-ucode/microcode_amd_fam15h.bin"
   CONFIG_EXTRA_FIRMWARE_DIR="/lib/firmware"
 

diff --git a/drivers/base/firmware_loader/Kconfig b/drivers/base/firmware_loader/Kconfig
index 5b24f3959255..de4fcd9d41f3 100644
--- a/drivers/base/firmware_loader/Kconfig
+++ b/drivers/base/firmware_loader/Kconfig

@@ -29,8 +29,10 @@ if FW_LOADER
 config FW_LOADER_PAGED_BUF
 	bool
 
-config EXTRA_FIRMWARE
-	string "Build named firmware blobs into the kernel binary"
+config FW_LOADER_BUILTIN
+	bool "Enable support for built-in firmware"
+	default n

n is always the default, no need to list it again.

Oh, alrighty, I'll remove that line.

quoted

quoted

+	depends on FW_LOADER=y

I don't see what this gets us to add another config option.  Are you
making things easier later on?

This makes a few things clearer for both developers and users.
The code in question is a *feature* *only* when FW_LOADER=y, by
adding a new kconfig to represent this and clearly makeing it
depend on FW_LOADER=y it let's us:

  o Clarify that support for built-in firmware requires
    the firmware loader to be built-in to the kernel

That is good.

  o By default we now always skip built-in firmware even if a FW_LOADER=y

I do not understand, why would we ever want to skip built-in firmware?

  o This also lets us make it clear that the EXTRA_FIRMWARE_DIR
    kconfig entry is only used for built-in firmware

How was it ever used for anything else?  :)

The above is not easily obvious to developers (including myself when
I was reviewing this code) or users without this new kconfig entry.

Should I re-send by just removing the one line you asked for?

I can not take this as-is, so yes :)

thanks,

greg k-h